The present invention relates to apparatus for controlling temperature on a drying machine for running yarn sheets, and more particularly relates to apparatus which, on a continuous hot air type drying machine for running yarn sheets usually annexed to such a textile processing machine as a sizing machine, controls properly and fully automatically the inside temperature of the machine in accordance with the varying running conditions of the machine.
Generally, in conventional continuous hot air type drying machines for yarn sheets after sizing, the supply rate of hot air into the drying chambers, in other words the supply rate of thermal energy into the drying chambers, is maintained substantially constant irrespective of the running condition of the machine, i.e., high speed running, low speed running and stoppage of the running.
This constant supply rate system naturally causes differences in the drying effect on the yarn sheet in accordance with the difference in the running condition of the yarn sheet. Therefore, when the yarn sheet is processed through the drying machine at relatively high and relatively low speeds occurring alternately, there will be produced a considerable fluctuation in the drying effect on the yarn sheet in the lengthwise direction thereof. Such fluctuation in the drying effect along the length of the yarn sheet often tends to cast an ill influence upon the processing of the yarn sheet in the subsequent process steps. For example, when such a longitudinal fluctuation appears on the yarn sheet during the drying process and after sizing, frequent yarn breakages will occur in the subsequent weaving process and such frequent yarn breakages inevitably lead to degraded quality of the resulting products, lowered operational efficiency of the weaving process and seriously increased labour necessary for fixing of the yarn breakages and removal of defects appearing on the final products.
The constant supply rate system is accompanied with further drawbacks, i.e., loss of thermal energy, causing undesirable lowering of thermal efficiency in the drying operation. That is, under some situations, an unnecessarily excessive quantity of thermal energy is supplied into the drying chamber.
The primary object of the present invention is to provide an apparatus capable of freely adjusting the supply rate of thermal energy into the drying chamber in accordance with the running condition of the drying machine, thereby eliminating the above-described drawbacks inherent to the continuous hot air type drying machines of the conventional type.
Another problem arising in connection with the continuous hot air type drying machine is the condition of the yarn sheet within the drying chamber when the machine stops running. As the machine stops running, the yarn sheet naturally stops running and some longitudinal portion thereof remains at a standstill within the drying chamber. On the other hand, as hot air has been supplied into the drying chamber continuously throughout running of the machine, air of a relatively high temperature remains in the drying chamber just after the machine has stopped running. Such hot air may cause fatal thermal damage to the portion of the yarn sheet remaining at a standstill in the drying chamber. Therefore, it is preferable to lower the temperature of the air in the drying chamber as quickly as possible after the machine has stopped running.
It is another object of the present invention to provide an apparatus capable of positively lowering the temperature of the air and the portion of the yarn sheet in the drying chamber as quickly as possible just after the drying machine has stopped running.